Mount for periscopic sextants



May 22, 1951 V. E. CARBONARA ET AL MOUNT FOR PERISCOPIC SEXTANTS 3Sheets-Sheet 1 Filed July 2, 1948 May 22, 1951 v. E. CARBONARA ETAL2,554,010

MOUNT FOR vPERIscoPIc sExTANTs Filed July 2, 1948 3 Sheets-'Sheetv 2 wwwMay 22, 1951 v. E. cARBoNARA ET A1. 2,554,010

MOUNT FOR PERISCOPIC SEXTANTS Patented May 22, 1951 MOUNT FOR PERISCOPICSEXTANTS Victor E. Carbonara, Manhasset,

and Ervin Douglas MacDonald, East Williston, N. Y., assignors, by mesneassignments, to Kollsman instrument Corporation, Elmhurst, N. Y., a

corporation of New York Application July 2, 1948, Serial No. 36,608

7 Claims.

VThis invention relates to a mount for a periscopic sextant particularlyadapted for use in aircraft wherein the seXtant is projected through theaircraft skin and eliminates the transparent astrcdome and hand heldsextant.

An object of the invention is to provide a mount for a periscopicsextant providing means for locking the sextant in a retracted positionso as to prevent accidental release by which the instrument could beinjured in a fall and also to permit holding of the sextant in the mountbut in a retracted position.

Another object of the invention is a mount for a periscopic sextantwhich will facilitate the insertion of the sextant within the mount andits projection through the aircraft skin without substantial loss ofcabin air in a pressurized aircraft.

Another object of the invention is a mount for a p-eriscopic seXtantwhich will permit not only rotation of the sexta-nt about thelongitudinal axis of the periscope but also universal tilting of theinstrument through a limited arc.

Another object of the invention isthe provision of a mount for aperiscopic sextant'in which the sextant is indexed within the mount Withrespect to the longitudinal axis of the aircraft and an azimuth scale soas to give the azimuth reading of the line of sight of the seXtant.

Another object of the invention is a mount for a periscopic sextantwhich provides `for the presetting of a computed azimuth for the line ofsight of the sextant in conjunction of the azimuth of the true aircraftheading or, conversely, the use of the azimuth angle of a celestial bodyto check the aircraft compass and its heading.

Other objects and features of the invention will be readily apparent tothose skilled in the art from the specification and appended drawingsillustrating certainy preferred embodiments in which:

Figure l is an elevational view of a mount for a periscopic sextantaccording to the present invention including the shutter assembly andshowing the projected sextant in broken lines.

AFigure 2 vis a bottom plan View of the'mount on the line vII-II ofFigure 1.

Figur-e 3 is a view showing the shutter assembly in section and thesextant seat in elevation and with the sextant indicated in broken linesVinfretracted butmounted position..

Figure 4is a viewsimilarto Figure 3 -1 ing the shutter open and the.sextant :i enge-d posing?? -'..`=.1ig i5. iaiseiieiulrieui tiene@portion of the sextant mount, the view being taken on right angle planesV-V of Figure 2 to show the gimbal ring arrangement.

Figure 6 is an elevational view of the seat portion of the seXtantmount.

Figure '7 is an enlarged detailed sectional view of the mechanism forlocking the instrument against rotation and taken on the line VII-Vil ofFigure 6.

Figure 8 is a detailed view on the line VIII-VIII of Figure 7.

The periscopic sextant mount according to this invention comprises ashutter assembly housing indicated generally at I and an instrument'seatindicated generally at 2. The shutter housing and instrument seat areconnected together as by studs 3 directed through flanges upon astationary mounting ring 4. i

As shown in Figures 3 and 4, the shutter housing is connected bysuitable screws, not shown, to the outer skin 5 of an aircraft.v Theshutter housing includes a top wall provided with an opening I adaptedto be closed by a shutterv 8 and through which the end of the tube ofthe periscopic sextant projects. At the exterior of the housing, thereis provided a manual operating handle 9 mounted on a shaft II pivoted inthe opposite side walls of the housing. Upon the shaft II there ismounted an internal lever I2 connected through a link I3 to the shutter8. The shaft lli pivotally connecting the link I3 to the shutter 8 hasend portions riding in suitable guide slots i5 in the opposite sidewalls of the shutter housing. Similarly, the left hand side of theshutter, as shown in Figures 3 and 4, is provided with a shaft or pinIii riding in guide slots I 'i in the opposite side walls of thehousing. An over-center spring arrangement l'serves to hold the shutterin its extreme closed and open positions. l

The operation of the shutter will =be readily apparent from aninspection of Figures 3 and 4 as rotation of the operating handle 9 in acounterclockwise direction from the position of Figure 3 to that ofFigure 4 will move the shutter 8 from its Figure 3 position, closing the'opening l', into its open Figure 4 position, the `over-center spring I8serving to maintain the parts in either of these extreme positions inWhchthe uallyplaced.

The seat` portion of the Sextantgmo nt vwill be best understood from aninspection .0f vthe drawing; L'Ilie tube portion of'ffth sortant isadapted tcbezdisposedthlfoug asleeye V is;rotatably:mountedgbylldcarings ,il and'Z .with

in a ring 23. Outside of the ring 23 is a second 'ring 24 pivotedthereto by oppositely dispose-:l trunnions 25, of which one only isshown in Figure 5, the trunnions 25 thereby providing for rotation ofthe ring 2d about the ring 23 in one plane. At the outside of the ring25 is a third ring 2E pivotally' secured to the ring 24 by a pair ofoppositely directed trunnions 21, of which one only is shown in Figure5, with the trunnions 21 disposed in a plane at 9 with respect to theplane of trunnions 25. The ring' 2S is shock mounted by cushion Washers23 Within the stationary mountingr ring 4. With the ring and trunnionarrangement above described, it is seen that there is provided a gimbalmounting for the sleeve i9 permitting universal tilting thereof and ofthe instrument therein in all directions through a limited arc. A seriesof internal annular grooves are provided in the inner surfaces of thegimbal rings, as shown in Figure 5, in order to reduce the air leakagebetween adjacent gimbal rings.

Mounted at the lower portion of the ring 23, by means or studs 25, is arotatably adjustable ring 3l carrying a datum index line 32 (Figure 2)The ring 3i is clamped in its adjusted position by means of the studs 2Qand the clamping ring 33. Outside of the ring 3| bearing the datum indexline is a rotatable ring 3 bearing azimuth indicia 35. Connected to theazimuth ring 55 is a knurled ring 36 for manually rotating the azimuthring. The azimuth ring 34 has a spring slip connection at 3? (Figure 7)with respect to the clamping ring 53 so as to be freely rotatable atWill regardless of the clamping of the datum index line ring 3i. At thebottom of the seat there is provided a rotatable ring 33 rigidly mountedto the sleeve i9 by means of studs 55 threading into a ring lli threadedon the outside of the sleeve i9, the ring 38 and sleeve i9 being indexedby the pin and slot connection shown at 52. At the outside of the ring38 is a knurled gripping portion i3 and rigidly connected to the ring 3Bis a transp-arent shield le bearing a lubber line indicated at 45 inFigure 2.

The bottom of the ring 33 is provided with a circular flange 46 havingcut therethrough a pair of slots 51 and 48. The slot lll communicatesWith an annular cut out porton 59 in the bottom of the sleeve i9 andthis in turn communicates with an elongated groove i in the interiorWall of the sleeve i5, the groove 5l being spaced a substantal angulardistance from the slot Il?. Above the slot 5B the sleeve i9 is providedwith a mating slot 52 into which projects the end of a locking pin 53biased inwardly by a spring 543 and provided with a manual handle forretracting the pin. Adjacent the groove 5I and Within the annular cutoutportion 45 there is provided a second locking device 55 which may be aduplicate of the locking pin 53 or may be a simple spring pressed ball.

As shown in broken lines in Figure 5, the sextant is in its projectedposition with a pin 51 rigid With the periscopic tube shown disposedadjacent the upper end of the groove 5I in sleeve i3. Within the cutoutportion 52 in the sleeve i9, there is shown in broken lines a lockingand index plate 5t rigid with the periscopic tube and into which the endof the locking pin 53 projects.

Referring to Figures 7 and 8, there is shown means for locking thelsleeve l and the instrument therein against rotation, this lockingmeans comprising'a n'ia'nu'al handle 55 mounted upon a rotatablefshaft.5|.;,ivhio'r -is.tl'ireaded in `a ring tl. Above the shaft 6i is a slipspring ring S2 between the ring lll and the bottom part of the ring 23.As the handle 5S is rotated to rotate shaft El, the shaft 5i Will bemoved longitudinally into engagement with the ring 52 and will hencelock the sleeve I Si, ring 4l and ring 3S to the ring 23 which is heldagainst rotation about the longitudinal axis of the instrument althoughit may still tilt in its girnbal mounting.

The operation of the mount will now be described. A suitable opening iscut in the skin of the aircraft and the plate B of the shutter housingconnected thereto by screws. The seat portion of the mount may remainconnected to the shutter housing during this mounting in the aircrait.In View of the fact that the datum index mark 32 is adjustable, it isunnecessary to align any portion of the mount with the longitudinal axisof the aircraft in its initial mounting on the skin. The datum indexmark should then be aligned with the longitudinal axis of the aircraftand this will be a permanent adjustment since 1t need be done but oncefor any mount installation. Tn adjusting the position of the datum indexmark, the sextant is inserted into the mount, as Will be hereinafterdescribed, and the sextant is then aligned with the longitudinal axis ofthe aircraft. This positions the lubber line 45 parallel with thelongitudinal aircrai t axis. Thereafter, the four screws 29 are loosenedand the ring 3i is rotated until the datum index line is coincident withthe luober line (the sextant being still aligned with the longitudinalaxis of the aircraft). The screws 25 are then tightened to lock the ring3i in position and this permanently adjusts the datum index line inalignment with the longitudinal axis of the aircraft.

In inserting the periscopic sextant into the mount, the pin 51 is passedthrough the slot 41 and the ring 38 rotated until locking means 56passes over the pin 51. If a locking pin as 53 is used, it Will bemanually retracted and if a spring pressed ball is used for the lockingmeans 56, a simple rotation of the ring will move it past the pin 51 onthe periscope tube. After this operation, the sextant is locked in itsretracted position and it may be left in this position indenitely, ifdesired, since it is held in position by engagement of the pin 51 Withthe flange 46. With the periscope in the mount in retracted position,the shutter 8 is opened by rotation of the handle 9 as indicated inFigures 3 and 4. Thereafter, the periscope will be moved upwardly intoits projected position with the pin 51 passing up the groove 5| in thesleeve I9` and the locking plate 58 entering the slot 52 in the sleevei9 and interlocking With the pin 53 to lock the sextant in its projectedposition. In its projected position, the sextant may be turned about itslongitudinal axis by rotation of the sleeve I9 and it may be tilted inthe gimbal mounting of the sleeve. The vertical rotation of the angle ofsight of the sextant Will, of course, be a matter of its internalconstruction, a sextant of this type being shown in the copendingapplication of Victor E. Carbonara, Serial No. 33,345 filed June 16,1948, entitled Periscopic Sextant.

To remove the sextant from its mount, the operation is the reverse ofthat described for it insertion. The locking pin 53 must be retracted topermit the sextant Ato be lowered until the pin 51 engages the flange46. Thereafter, the shutter 8 should be closed and .the sextant rotateduntil the pin 51 again registers'with the slot 41,v

whereupon the. instrume1.1t "wir heffbodlywemoved. It will be seen thatwith the flange d6, pin 51. and the locking means 5%, it is impossiblefor the se-Xtant to accidentally fall from its mount if the locking pinb3 is retracted, and, furthermore, that when in retracted position itwill be maintained therein until it is deliberately removed by manualmanipulation.

I f the sextant is inserted into the mount in retracted position beforethe shutter 8 is opened, it, Will be seen that there will be a minimumloss of cabin air from a pressurized cabin when the Sextant is placed inits projected position. It will also be noted that the gimbal rings areprovided With annular grooves to minimize loss of vair thereabout. Y

One feature of the mount according to this invention lies in the meansfor placing the sextant in position for observation of a celestial bodyWithout the necessity of scanning the sky and also for checking theaircraft compass and heading from observations of a celestial body.

The azimuth and altitude angles for the anticipated time of a futureobservation may be computed, the altitude angle set inthe sextant, and

the azimuth dial 34', 35 rotated so that the iixed datum index line 32indicates on the azimuth dial the aircraft heading with respect to truenorth, which will be the compass heading corrected for deviation andvariation. Then, if the sextant is rotated to place the lubber line i5upon the azimuth scale 35 at the computed value, the celestial body tobe observed should be Within the eld of View at the time of observation.This facilitates locating the celestial body in vthe cptical field byeliminating unnecessary scanning of the sky.

The true heading of the aircraft can be determined with the azimuthscale when it is used in conjunction with the procedure of taking altintilde angle bearings of celestial bodies to determine a x by lines ofposition, the true heading thus determined providing a check on thecompass. The sextant is directed to a star whose azimuth angle isdetermined from tables in conventional manner. The sextant is thenlocked in this position. The azimuth dial 3e, is rotated until theazimuth of the star appears opposite the lubber line 65. The trueheading of the aircraft is then indicated opposite the datum index line32. The difference between this indication, corrected for variation, andthe compass indication Will be the compass deviation.

It Will also be apparent that the azimuth scale will provide means foridentifying an unknown star since its azimuth may be determined from thereading of the azimuth scale opposite the lubber line when the trueaircraft heading is set at the datum index line 32.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparent to thoseskilled in the art and the invenu tion is to be given its broadestpossible interpretation Within the terms of the following claims:

What is claimed is:

1. In a mount for a periscopic sextant foraircraft, a stationary mountadapted to be connected to the aircraft skin under an opening therein, amovable shutter in said mount normally closing said opening, a rotatablesleeve in said mount aligned with said opening and adapted to receivethe periscopic tube of the sextant, means for locking the sextant tubewithin the sleeve butin retracted positonbeneath the shut` ter, meansfor opening the' shutter, and means for locking and indexing theperiscopic tube with respect to the sleeve in extended positionprojecting through the skin opening.

2. En a mount for a periscopic sextant for aircraft, a stationary mountadapted to `be connected to the aircraft skin under an opening therein,a movable shutter in said mount normally closing said opening, arotatable sleeve in said mount aligned with said opening and adapted to.receive the periscopic tube of the sextant, means for locking thesextant tube Within the sleeve but in retracted position beneath theshutter, means for opening the shutter, and means for locking andindexing the periscopic tube With respect to the sleeve in extendedposition projecting through the skin opening, said means for locking theperiscope in retracted position including pin and slot connectionsrequiring relative rotation Yof the sleeve and periscope tube before thetube is in a position to be projected.

3. In a mount for a periscopic sextant for aircraft, a stationary mountadapted to be connected to the aircraft skin under an opening therein, amovable shutter in said mount normally closing said opening, a rotatablesleeve in said mount aligned with said opening and adapted to receivethe periscopic tube of the sextant, means for locking the sextant tubewithin the sleeve but in retracted position beneath the shutter, meansfor opening the shutter, and means for locking and indexing theperiscopic tube with respect to the sleeve in extended positionprojecting through the slain opening, means for releasing the periscopictube from its locked projected position whereby the tube may be movedinto retracted position, and interlocking means preventing furtherremoval of the sextant until the sleeve and tube have been rotatedrelatively.

l. n a mount for a perscopic sextant for aircraft, a stationary mountadapted to be connected to the aircraft skin under an opening therein, amovable shutter in said mount normally closing said opening, a rotatablesleeve in said mount aligned with said opening and adapted to receivethe perscopic tube of the sextant, means for locking the sextant tubeWithin the sleeve but in retracted position beneath the shutter, meansfor opening the shutter, and means for locking and indexing theperiscopic tube with respect to the sleeve in extended positionprojecting through tle skin opening, said means for locking theperiscope in retracted position including pin and slot connectionsrequiring relative rotation of the sleeve and periscope tube before thetube is in a position to be projected and means for restraining thesleeve and periscopic tube against rotation when in retracted positionso as to prevent accidental release of the tube and sextant.

5. In a mount for a periscopic sextant for aircraft, a stationary mountadapted to be connected to the aircraft skin under an opening therein, amovable shutter in said mount normally closing said opening, a rotatablesleeve in said mount aligned with said opening and adapted to receivethe periscopc tube of the sextant, means for locking the sextant tubewithin the sleeve but in retracted position beneath the shutter, meansfor opening the shutter, and means for locking and indexing theperiscopic tube With respect to the sleeve in extended positionprojecting through the skin opening, a datum index line on said mount,an azimuth ring on said mount and freely rotatable relative thereto andcarrying azimuth indicia thereon, and a lubber line connected to saidsleeve and rotatable therewith, the azimuth indicia being positioned tobe read with respect to both said datum index and lubber lines, saidmeans for locking the periscope in retracted position including pin andslot connections requiring relative rotation of the sleeve and periscopetube before the tube is in a position to be projected.

6. In a mount for a periscopic sextant for aircraft, a stationary mountadapted to be connected to the aircraft skin under an opening therein, amovable shutter in said mount normally closing said opening, a rotatablesleeve in said mount aligned with said opening and adapted to receivethe periscopic tube of the sextant, means for locking the sextant tubewithin the sleeve but in retracted position beneath the shutter, meansfor opening the shutter, and means for locking and indexing theperiscopic tube with respect to the sleeve in extended positionprojecting through the skin opening, a pair of rings carried by saidmount at the exterior of said sleeve, a datum index line on one of saidrings, means for adjustably locking said one ring in indexed normallynon-rotatable position, azimuth indicia on the second of said rings, thesecond of said rings being mounted to be freely rotatable with respectto said mount and datum index line ring, and a lubber line connected tosaid sleeve so as to be rotatable therewith, the azimuth indicia beingpositioned to be read with respect to both said datum index and lubberlines, means for releasing the periscopic tube from its locked projectedposition whereby the tube may be moved into retracted position andinterlocking means preventing further removal f the sextant until thesleeve and tube have been rotated relatively.

7. In a mount for a periscopic sextant for aircraft, a stationary mountadapted to be connected to the aircraft skin under an opening therein, amovable shutter in said mount normally closing said opening, a rotatablesleeve in said mount aligned with said opening and adapted to receivethe periscopic tube of the sextant, means for locking the sextant tubeWithin the sleeve but in retracted position beneath the shutter, meansfor opening the shutter, and means for locking and indexing theperiscopic tube With respect to the sleeve in extended positionprojecting through the skin opening, a pair of rings carried by saidmount at the exterior of said sleeve, a datum index line on one of saidrings, means for adjustably looking said one ring in indexed normallynon-rotatable position, azimuth indicia on the second of said rings, thesecond of said rings being mounted to be freely rotatable with respectto said mount and datum index line ring, a lubber line connected to saidsleeve so as to be rotatable therewith, the azimuth indicia beingpositioned to be read with respect to said both datum index and lubberlines, means for locking the rotatable sleeve at will in any position,said means for lock`- ing the periscope in retracted position includingpin and slot connections requiring relative rota= tion of the sleeve andperiscopic tube before the tube is in a position to be projected andmeans for restraining the sleeve and periscopic tube against rotationwhen in retracted position so as to prevent accidental release of thetube and sextant.

VICTOR E. CARBONARA.

ERVIN DOUGLASv MACDONALD.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 867,982 Lake Oct. 15, 19071,341,683 Styli June 1, 1920 2,037,162 Gent Apr. 14, 1936 2,389,852Hagner Nov. 27, 1945

